package pat;

import java.util.Scanner;

class mars {
	public static void main(String args[]) {
		int sum = 0;
		double total = 0;
		int j = 0;
		int k = 0;
		Scanner s = new Scanner(System.in);
		int n = s.nextInt();
		s.nextLine();
		int a[] = new int[2 * n];
		char b[] = new char[2 * n];
		String str = s.nextLine();
		for (int i = 0; i < str.length(); i++) {

			if (str.charAt(i) >= '0' && str.charAt(i) <= '9') {
				sum = sum * 10 + str.charAt(i) - '0';
			} else if (str.charAt(i) == '-') {
				b[j] = '-';
			} else {
				j++;
				sum = 0;
			}
			a[j] = sum;
		}

		for (int i = 0; i < a.length-2;) {
			total += (double) a[i] / a[i + 1];
			i += 2;
			System.out.print(b[i]);
		}
		System.out.print(total);

	}
}
